In general, an intake manifold of a vehicle is mounted at the head of an engine and serves to supply air and fuel required for combustion of the engine into a cylinder.
Such an intake manifold has an air inlet formed at one side thereof, through which air is introduced from outside, and the air inlet has a throttle body mounted thereon such that air is introduced through the throttle body. The intake manifold includes a plenum chamber which provides a predetermined space in which the introduced air can stay. Furthermore, the intake manifold includes branched flow paths, that is, a plurality of runners formed at one side of the plenum chamber so as to properly distribute and guide air to a plurality of cylinders.
Since the intake manifold has a large influence on the volume efficiency and output of the engine, a variety of researches have been conducted on the intake manifold. Furthermore, since air mixture passed through the intake manifold does not normally flow but intermittently flows at each cycle, the intake manifold must be designed in consideration of pulsation or interference, in order to increase the volume efficiency.
Meanwhile, the amount of air mixture introduced through the intake manifold is related to the operation condition of the engine. Thus, when the operation range of the engine corresponds to a low-speed and low-load range, a small amount of air mixture flow is required, and when the operation range of the engine corresponds to a high-speed and high-load range, a large amount of air mixture flow is required within a short time, while intake resistance is minimized. For this reason, a variable intake manifold has been recently developed, which is variably controlled according to the operation state of the engine.
Recently, research has been actively conducted on a variable intake manifold to which a VIS (Variable Intake System) is applied. The variable intake manifold can variably adjust the volume of a runner according to the operation condition of an engine, in order to increase the efficiency of the engine. As the volume of the variable intake manifold is variably adjusted according to the operation condition of the engine, the improvement in torque and performance of the engine can be expected.
Such a variable intake manifold is disclosed in Korean Patent Laid-open Publication Nos. 10-2005-0115072 and 10-2006-0003513.
FIG. 1 is a perspective view of a conventional actuator for an intake manifold, FIG. 2 is an expanded view of the actuator for the intake manifold of FIG. 1, and FIG. 3 is an exploded view of the actuator for the intake manifold of FIG. 1.
Referring to FIGS. 1 to 3, the conventional actuator 100 for an intake manifold includes a solenoid valve 110, a vacuum actuator 120, a first flow path 130, and a second flow path 140. The solenoid valve 110 is installed outside the intake manifold 101. The actuator 100 for the intake manifold rotates a valve arranged in a runner of the intake manifold 101 such that an air intake path can be variably changed in the runner. That is, the actuator 100 for the intake manifold may variably control the air intake path inside the intake manifold 101 through the vacuum actuator 120 which is coupled to the valve so as to rotate the valve.
The solenoid valve 110 is coupled to one side of the outside of the intake manifold 101. The solenoid valve 110 includes an intake port 111 and an exhaust port 112. The intake port 111 is connected to the vacuum actuator 120 through a first flow path 130, and the exhaust port 112 is connected to the intake manifold 101 through a second flow path 140. The solenoid valve 110 further includes a bracket 113 fixed to the intake manifold 101.
The vacuum actuator 120 is arranged on a side surface of the outside of the intake manifold 101, and coupled to the valve arranged in the intake manifold 101 through an operating bar 125. The vacuum actuator 120 may have a vacuum state formed through the solenoid valve 110. When the vacuum actuator 120 is set in the vacuum state, the vacuum actuator 120 rotates the valve arranged in the intake manifold 101.
The first flow path 130 connects the intake port 111 of the solenoid valve 110 to the vacuum actuator 120 outside the intake manifold 101. The second flow path 140 connects the exhaust port 112 of the solenoid valve 110 and the intake manifold 101 to each other. That is, the solenoid valve 110 and the vacuum actuator 120 are coupled to the outside of the intake manifold 101, and the actuator 100 for an intake manifold includes two or more flow paths which communicate with the vacuum actuator 120 through the solenoid valve 110 from the intake manifold 101.
The actuator 100 for an intake manifold requires the first flow path 130 connected to the vacuum actuator 120 from the solenoid valve 110 and the second flow path 140 connected to the solenoid valve 110 from the intake manifold 101. That is, the actuator 100 for an intake manifold has a complex structure in which two or more flow paths are formed outside the intake manifold 101. Furthermore, since the actuator 100 for an intake manifold requires a separate bracket 113 for fixing the solenoid valve 110 to the intake manifold 101, the actuator 100 has a complex structure, and inevitably increases in weight.